1. Field of the Invention
The present invention relates to a liquid crystal display device.
2. Description of the Related Art
A liquid crystal cell of a general liquid crystal display device has a structure in which a liquid crystal layer is held by transparent substrates such as glass substrates. The liquid crystal display device includes a liquid crystal panel configured such that a polarizer, or a polarizer and a retardation plate, are disposed on the front and back of the liquid crystal cell.
In a first example, a liquid crystal display device includes a backlight unit as a light source on a back surface of a liquid crystal panel, which is on a side opposite to an observer. In a second example, a liquid crystal display device makes use of an external light source such as room light, in addition to a backlight unit.
In a liquid crystal display device which is capable of performing three-dimensional image display, and a liquid crystal display device which is capable of controlling a viewing angle, a liquid crystal panel which makes use of a backlight unit or an external light source is configured to control, according to purposes of display, an emission angle of light which is emitted to the outside from a front surface of the liquid crystal panel, which is on an observer side.
Various display methods are known for liquid crystal display devices, or display devices, which are capable of performing three-dimensional image display. These display methods include methods using glasses, and methods not using glasses. The methods using glasses include an anaglyph method which makes use of a difference in color, or a polarization-glasses method which makes use of polarization. In the method of using glasses, it is necessary for an observer to wear purpose-specific glasses at a time of three-dimensional image display, and this is troublesome. In recent years, there has been an increasing demand for methods which require no glasses.
In order to adjust the angle of light which is emitted from the liquid crystal panel to a single observer or plural observers (hereinafter, in some cases, “single observer” and “plural observers” are referred to as “two-view type” and “multi-view type”, respectively), a study has been made of a technique of providing an optical control element on the front surface or back surface of the liquid crystal panel.
There is a case in which the optical control element is used in a liquid crystal display device which is capable of performing three-dimensional image display and requires no glasses.
An example of the optical control element is a lenticular lens which is configured such that optical lenses are arranged two-dimensionally, and realizes regular refraction. The lenticular lens is used such that a transparent resin or the like is processed in a sheet shape and attached to the front surface or back surface of a liquid crystal display device. Patent document 1 (Japanese Patent No. 4010564) and patent document 2 (Japanese Patent No. 4213226) disclose three-dimensional image display techniques using lenticular lenses (lenticular screens). Prism sheets including convex lenses are disclosed in patent documents 3 to 8 (Jpn. Pat. Appln. KOKAI Publication No. 2010-506214, Jpn. Pat. Appln. KOKAI Publication No. 2010-524047, Jpn. Pat. Appln. KOKAI Publication No. 2010-541019, Jpn. Pat. Appln. KOKAI Publication No. 2010-541020, Japanese Patent No. 4655465, and Japanese Patent No. 3930021).
The relationship between various arrangements of pixels (color pixels) of color filters and light-ray control elements (lenticular sheets) including aperture portions in a direction of the arrangement is disclosed in patent document 9 (Jpn. Pat. Appln. KOKAI Publication No. 2008-249887).
In addition, a technique of successively disposing color filters of the same color in a lateral direction is disclosed, for example, in Claim 1 of patent document 10 (Jpn. Pat. Appln. KOKAI Publication No. 2009-3002).